The Childhood of Adult-Onset Asthma and the Asthma/Chronic Obstructive Pulmonary Disease Overlap

Adult asthma is a heterogeneous condition and, in a significant proportion of patients, the disease first manifests during childhood. Recent evidence suggests, however, that even in bona fide adult-onset asthma, the roots of the disease may be found in early life. In longitudinal studies, patients with adult-onset asthma were more likely to have early life wheezing and bronchial hyperresponsivess at age six than subjects without asthma. Adult-onset asthma has also been consistently associated with preceding reports of both atopic and non-atopic rhinitis, suggesting that an alteration in mucosal/innate immunity may be common to both conditions. Of particular interest are the potential early origins of the asthma/chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS). Many patients with childhood-onset asthma reach the plateau phase of lung function with significant airflow limitation and are thus likely to eventually reach the levels of forced expiratory volume in 1 second and forced expiratory volume in 1 second/forced vital capacity ratio that codify the diagnosis of COPD, even after normal rates of age-related lung function decline. Active smoking has been shown to have synergistic effects with both a history of childhood asthma and with a history of lower respiratory illnesses due to the respiratory syncytial virus in determining increased airway narrowing and a diagnosis of asthma in early adult life. Asthma diagnosis, in this case, could potentially be a surrogate for the first clinical manifestations of chronic obstructive pulmonary disease. It is thus plausible to surmise that strategies for the prevention of ACOS will need to reach back to active avoidance of risk factors that may predispose for this condition during the growing years. Among these strategies, development of a vaccine against respiratory syncytial virus, decreased exposure to air pollution, and smoking cessation targeted to adolescents and young adults with asthma should be major priorities.